PHOTOCHEMICAL SENSORS BASED ON AMORPHOUS-SILICON THIN-FILMS

Hydrogenated amorphous silicon photochemical sensors based on Pd metal /insulator/semiconductor (Pd-MIS) structures were produced by plasma e nhanced chemical vapour deposition (PECVD) with two different oxidised surfaces (thermal and chemical oxidation). The behaviour of dark and illuminated current-voltage characteristics in air and in the presence of a hydrogen atmosphere is explained by the changes induced by the g ases adsorbed, in the work function of the metal, modifying the electr ical properties of the interface. The photochemical sensors produced p resent more than two orders of magnitude variation on the reverse dark current in the presence of 400 ppm hydrogen. When the sensors are sub mitted to light it corresponds a decrease of 45% on the open circuit v oltage. (C) 1998 Elsevier Science S.A. All rights reserved.